Myriad negative health outcomes are rooted in risky decisions made during adolescence, such as sexually transmitted disease, drug abuse, and vehicular accidents to name a few. The proposed research seeks to shed light on some of the situational and physiological underpinnings of adolescent risk taking behavior. Steinberg (2007;2008) posits that adolescents take more risks than adults because of an imbalance between their socio-emotional and cognitive-control systems. The socio-emotional system matures at puberty, leading to increased reward-seeking from childhood to adolescence. However, the cognitive-control system continues maturing through adolescence into young adulthood, causing adolescents to be less sensitive to the costs associated with taking risks. The proposed work explores whether the experience of social evaluative threat exacerbates the imbalance between the socio-emotional and cognitive-control systems. This research will be the first to directly explore the impact of social evaluative threat, even though peer pressure, a type of social evaluation, has been linked to increased risk taking in adolescents. Physiological reactivity will be measured in an effort to examine the underlying biological mechanism(s) of the effect of social evaluative threat on risk taking. This method circumvents potential distortions associated with self-reports, such as impression formation and social norm adherence. The primary hypotheses of this research plan are: 1.) the experience of social evaluative threat will increase risky behavior by increasing attention to rewards while decreasing attention to costs, and 2.) physiological threat responses will mediate the link between social evaluative threat and risk taking, such that physiological threat responses will lead more risk taking. Potential moderators will then be explored. Because males tend to take more risks than females (Byrnes, Schafer, &Miller, 1999), the effects of sex will be examined. Age effects will be explored because the cognitive-control system matures throughout adolescence into adulthood. Furthermore, this work finds physiological threat reactions lead to more increased risk behavior, race may emerge as a significant moderator because African-Americans tend to experience more life stress and are at greater risk for hypertension than European-Americans (Anderson, 1989). To date, approaches designed to reduce adolescent risk taking, such as education and abstinence programs, have largely been unsuccessful because of a lack of understanding why adolescents take risks. By identifying the underlying causes of adolescent risk behavior, this research will help improve health outcomes by encouraging the development of intervention strategies based on treating the causes rather than the symptoms of risk taking. PUBLIC HEALTH RELEVANCE: Adolescent risk taking has a profound negative health impact, and efforts to develop intervention strategies have largely been unsuccessful because research has yet to identify the underlying causes of adolescent risk behavior. The current work seeks to shed some light on the situational and biological underpinnings of adolescent risk taking. If researchers understand why adolescents take risks, successful interventions can be developed to treat the causes of risk behavior rather than expending resources treating symptoms.